thread monitoring tweaks

blocks.js

@@ -2289,7 +2289,7 @@ BlockMorph.prototype.userMenu = function () {
         menu.addItem(
             (proc ? this.fullCopy() : this).thumbnail(0.5, 60),
             function () {
-                var cpy = this.fullCopy(),
+                var cpy = myself.fullCopy(),
                     nb = cpy.nextBlock(),
                     ide = myself.parentThatIsA(IDE_Morph);
                 if (nb) {nb.destroy(); }

threads.js

@@ -1208,7 +1208,8 @@ Process.prototype.doShowVar = function (varName) {
     if (this.homeContext.receiver) {
         stage = this.homeContext.receiver.parentThatIsA(StageMorph);
         if (stage) {
-            target = varFrame.find(name);
+            target = varFrame.silentFind(name);
+            if (!target) {return; }
             // first try to find an existing (hidden) watcher
             watcher = detect(
                 stage.children,